Remove TravisCI.org integration

[Coduz]

This PR removes all references to TravisCI.org and therefore the integration.
Since #3182 we are using Github Actions as CI tool.

Related Issue
None

Description of the solution adopted
Removed all references.
I did not opened a BugZilla issue to remove the project tracking since TravisCI.org going to be dismissed soon.
https://mailchi.mp/3d439eeb1098/travis-ciorg-is-moving-to-travis-cicom?e=%5BUNIQID%5D

Screenshots
None

Any side note on the changes made
I've fixed and organized badges.
Jenkins one was failing to fetch status.

[codecov]

Codecov Report

Merging #3237 (72bcd37) into develop (91a62ae) will decrease coverage by 0.02%.
The diff coverage is n/a.

@@              Coverage Diff              @@
##             develop    #3237      +/-   ##
=============================================
- Coverage      58.20%   58.17%   -0.03%     
- Complexity      2850     2853       +3     
=============================================
  Files           1273     1273              
  Lines          26991    26991              
  Branches        2339     2339              
=============================================
- Hits           15709    15703       -6     
- Misses         10378    10383       +5     
- Partials         904      905       +1     

Impacted Files	Coverage Δ	Complexity Δ
...ua/broker/core/listener/DeviceMessageListener.java	60.46% <0.00%> (-6.98%)	0.00% <0.00%> (ø%)
...ce/management/commons/call/DeviceCallExecutor.java	62.79% <0.00%> (-4.66%)	0.00% <0.00%> (ø%)
...pse/kapua/commons/service/internal/ServiceDAO.java	73.58% <0.00%> (-1.26%)	0.00% <0.00%> (ø%)
...atch/persistence/jpa/JpaExecutionInstanceData.java	90.24% <0.00%> (+2.43%)	23.00% <0.00%> (+1.00%)
.../DeviceManagementOperationRegistryServiceImpl.java	69.64% <0.00%> (+3.57%)	14.00% <0.00%> (+2.00%)